Overheat at 70 mph, then instant normal temp
#1
Overheat at 70 mph, then instant normal temp
2000 Grand Marquis, new electric fan, radiator, thermostat and water pump & temp probe. Works fine in town with A/C on, on the highway at 70 MPH thermostat will flash at full heat deflection, then drop to normal temp. car will falter or limp mode while gauge and engine light flash and alarm. Pull over and let idle for a few minutes and operates fine as long as I stay below highway speeds? Still blows heat while showing extra hot.
#2
Overheating under those conditions usually is a waterflow issue.You could confirm the temperature with a scan tool under those driving conditions. What I would look at is the lower hose colapsing, limiting the flow of coolant at those speeds. I would repace it if it doesn't contain a coil spring inside.
#3
2000 Grand Marquis, new electric fan, radiator, thermostat and water pump & temp probe. Works fine in town with A/C on, on the highway at 70 MPH thermostat will flash at full heat deflection, then drop to normal temp. car will falter or limp mode while gauge and engine light flash and alarm. Pull over and let idle for a few minutes and operates fine as long as I stay below highway speeds? Still blows heat while showing extra hot.
#8
If you have a scan tool, I would connect it, drive it at higher speeds and see what temperature the computer is actually seeing from the sensor. If you had a blocked converter, I doubt you would be able to obtain 70 mph. A vacuum gauge can verify any appreciable restriction in the exhaust system.Some engines have two coolant temperature sensors, one for gauge and the other for the computer. If your radiator has calcified deposits blocking the flow of water through the water tubes, I doubt any cleaner in a can is going to clean it.
You have to determine if the engine is producing too much heat, false information as determined by the computer or a cooling system not performing.
You have to determine if the engine is producing too much heat, false information as determined by the computer or a cooling system not performing.
Last edited by raski; 10-19-2022 at 06:05 AM.
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Dobie1966
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09-09-2014 06:30 PM